A head-up display that allows an observer to visually recognize a virtual image in a viewpoint region of the observer is provided. The head-up display includes: a display device that has a display surface and displays an image on the display surface; and a first optical system that has a concave mirror, and a lens condensing the light and disposed between the concave mirror and the display surface. The first optical system causes a beam exiting from the display surface to form an intermediate image via the lens and the concave mirror, the intermediate image being enlarged from the image displayed on the display surface.

A stop, such as a numerical aperture stop, obscuration stop or false-light stop, for a lithography apparatus, includes a light-transmissive aperture and a stop element, in which or at which the aperture is provided. The stop element is opaque and fluid-permeable outside the aperture.

An imaging optical unit serves within a metrology system for examining a lithography mask. The lithography mask can be arranged in an object field of the imaging optical unit. The object field is defined by two mutually perpendicular object field coordinates. The imaging optical unit has an aperture stop of which the aspect ratio in the direction of the two object field coordinates differs from 1. This results in an imaging optical unit which can be used for the examination of lithography masks that are designed for projection exposure with an anamorphic projection optical unit.

In a method for three-dimensionally measuring a 3D aerial image in the region around an image plane during the imaging of a lithography mask, which is arranged in an object plane, a selectable imaging scale ratio in mutually perpendicular directions (x, y) is taken into account. For this purpose, an electromagnetic wavefront of imaging light is reconstructed after interaction thereof with the lithography mask. An influencing variable that corresponds to the imaging scale ratio is included. Finally, the 3D aerial image measured with the inclusion of the influencing variable is output. This results in a measuring method with which lithography masks that are optimized for being used with an anamorphic projection optical unit during projection exposure can also be measured.

A projection optical system comprises an image forming unit that forms an image; a refractive optical system including a plurality of lenses that enlarges and projects the image on a screen; and a reflecting surface, wherein an intermediate image is formed between the refractive optical system and the reflecting surface, and the projection optical system satisfies conditions of 0.6<D/Did<0.8 and 2.5<Did/F<6, where Did represents a maximum paraxial image height of the intermediate image in a focusing state in which a projection image is maximum, D represents a maximum value of a distance between an optical axis and an intersection of a paraxial image surface and a light beam passing center of an aperture stop of the refractive optical system, and F represents a focal length of the refractive optical system in a focusing state in which the projection image is maximum.

The image display apparatus includes an optical system causing a light flux entering from an original image through an entrance surface to reflect at a part of reflective surfaces, causing the reflected light flux to form an intermediate image, and then causing the light flux to reflect at another part of the reflective surfaces and exit from an exit surface toward an exit pupil located in a first direction. The optical element includes a first optical portion, a second optical portion provided in a second direction orthogonal to the first direction with respect to the first optical portion, and a connection portion to be connected to a holding portion provided in the apparatus. The connection portion is formed on a side face of the first optical portion so as to be included within a maximum width of the second optical portion.

The image display apparatus includes an optical system causing a light flux entering from an original image by being transmitted through a fifth surface to reflect at a fourth surface, a third surface, a first surface and a second surface and then cause the light flux to be transmitted through the first surface and exit toward an exit pupil, causing the light flux to form an intermediate image and causing optical paths to intersect with each other. The optical system satisfies 0.62L12/f5.00 and 1.80L45/L125.00. When a distance between hit points of a central-view-angle principal ray on the surfaces is referred to as a hit point distance, L45 represents a hit point distance between the fourth and fifth surfaces, L12 represents a hit point distance between the first and second surfaces, and f represents a focal length of the optical system.

A field facet system for a lithography apparatus comprises: an optical element which comprises an elastically deformable facet portion having a light-reflecting optically active surface; and at least one actuating element for introducing a bending moment into the facet portion to deform the facet portion to change a radius of curvature of the optically active surface. The facet portion is curved in an arched manner in a plan view of the optically active surface. The rigidity of the facet portion as viewed along a longitudinal direction of the facet portion is variable so that a normal vector oriented perpendicularly to the optically active surface tilts exclusively about a spatial direction when the bending moment is introduced into the facet portion.

A head-up display is configured to project an image on a transparent reflection member to cause an observer to visually recognize a virtual image, and includes a display device configured to display the image, and a projection optical system configured to project the image displayed by the display device as the virtual image for the observer. The projection optical system is configured to form the image as an intermediate image, and includes a first optical element configured to condense light, a first lens configured to condense light, and a second optical element configured to diffuse light. The first optical element, the first lens, and the second optical element are disposed in this order along an optical path from the display device.

Devices, systems and methods related to all-reflective microscopes are described. The microscopes include an all-reflective off-axis optical system and is characterized with substantially zero chromatic aberration, low group delay dispersion and no central obscuration. One reflective microscope configuration includes a reflective objective subsection with at least three mirrors, where at least one mirror is off-axis and non-spherical. The reflective microscope also includes a reflective relay subsection with at least two minors having freeform surfaces and positioned to receive light from the reflective objective subsection. The reflective relay subsystem is configured to produce a magnification to allow coupling of light between two planes having differing beam sizes. The reflective microscope further includes an imaging subsection with at least one mirror having a freeform surface and positioned to receive light from the reflective relay subsection and to direct light received thereon in reflection in a direction of a sensor.